1. Field of the Invention
The present invention relates in general to improved draft arms for railway cars. More specifically, but without restriction to the particular use which is shown and described, this invention relates to a lighter weight draft arm.
2. Description of the Related Art
A railcar draft arm is a box-shaped member positioned between the center sill and the coupler of a railcar. A draft arm is located on each end of the center sill, which extends along the length of the railcar body, as part of the under frame; thus two draft arms are used with each railcar. The draft arms, as with the center sill, are welded to the under frame of the railcar body. The draft arms serve the multi-purpose of connecting the center sill to the railcar couplers and transmitting the draft and buff (longitudinal) loads through the railcar to the next railcar. In addition, the draft arm provides the connection between the railcar body and the trucks, which support the railcar body at both ends of the railcar.
At each end of the center sill, the draft arm is fitted and welded at its inboard end to the center sill. The outboard end of the draft arm has either a cast integral striker or a separate striker assembly that is fitted with and welded to the draft arm. A coupler assembly and its associated yoke are mounted to the outboard end of the draft arm, through the opening formed by the striker. The coupler assembly and yoke are secured to the draft arm by a draft key, which extends through a pair of aligned draft arm key slots, the striker key apertures and cooperating apertures in the coupler and yoke.
In addition to the pair of aligned draft key slots which are conventionally located in each of the side walls of the draft arm, the draft arm also includes front and rear draft lugs within the draft arm, a center plate, and a single hollow kingpin hole for receiving a kingpin or bolt extending from a railway car truck. The center plate provides the connection to the center bowl on the truck bolster.
Conventionally, draft arms are manufactured of cast steel. The draft arms therefore contribute a substantial part of the total weight of the railway car. Since there are weight limits placed on shippers of goods for preserving the safety and conditions of the track, the quantity of goods that may be placed in or on a railcar is affected by the weight of the railcar body, the trucks and other railcar components. Thus, a reduction in the weight of the railway cars, including the draft arms, will result in an increase in the total capacity of goods shipped by a rail line owner. Therefore, it is highly desirable to reduce the weight in the draft arms without a decrease in strength.